ferrix/README.md

# Ferrix BGP

Ferrix is a BGP daemon for Linux routers, written in Rust. It exchanges
routes with neighbors, filters them by policy and the RPKI, selects the
best path for each prefix, installs it in the kernel, and passes routes on
as BGP roles and communities permit. It aims to be small, safe, observable,
and configured from one file that can be read by someone who did not write
it.

## Status

Ferrix routes the author's network, AS210036: three routers carrying full
tables from transit providers, route servers at several Internet exchanges,
and bilateral peers, with routes reflected between the routers over iBGP.
It is young software all the same. Read the [limitations](#not-supported)
before relying on it, and treat version `0.x` as meaning that configuration
and APIs may still change between releases.

What it does:

- BGP-4 over IPv4 and IPv6, with four-octet AS numbers, multiprotocol
  reach for both families, IPv4 routes with IPv6 next hops (RFC 8950),
  route refresh, graceful restart and ADD-PATH receive.
- Import policy per neighbor: prefix limits, prefix and origin AS lists,
  bogon checks, AS path checks, and communities added on the way in.
- Route origin validation and ASPA path verification against an RTR cache.
- BGP roles (RFC 9234) and the Only to Customer attribute, with export
  limits as a second line of defence against route leaks.
- Best path selection and installation of the result in the Linux kernel
  over netlink, in a routing table of your choice.
- Route reflection between routers of the same AS, and passive neighbors.
- A status page, a JSON API, server-sent events, and Prometheus metrics.
- Graceful restart of the daemon itself for upgrades, with routes left in
  the kernel while it is away.

### Not supported

- Per-client best path selection for route servers, and ADD-PATH for
  advertised routes
- TCP-AO, TCP MD5, and GTSM
- Long-Lived Graceful Restart, BFD, and configuration changes without a
  restart
- Recursive resolution of next hops that are not directly connected
- Address families other than IPv4 and IPv6 unicast

## Building

You need a stable Rust toolchain from [rustup.rs](https://rustup.rs), and a
C compiler and `make` for the jemalloc allocator the daemon uses (for
example `build-essential` on Debian and Ubuntu, `base-devel` on Arch Linux,
or the Xcode command line tools on macOS). The Protocol Buffers compiler is
not needed: the configuration schema is compiled in pure Rust.

```bash
git clone https://git.rayhaan.net/rayhaan/ferrix.git
cd ferrix
cargo build --release --locked -p bgp
```

The binary is `target/release/bgp`. `--locked` builds with the dependency
versions recorded in `Cargo.lock`, which are the versions CI tested.

To try it without touching any router, run the quick-start configuration.
It listens on loopback, needs no privileges, and serves the status page at
<http://127.0.0.1:8080>; the [quick start
guide](docs/content/docs/getting-started/quick-start.md) adds a test peer
that announces routes to it.

```bash
target/release/bgp --check docs/examples/quick-start.textpb
target/release/bgp docs/examples/quick-start.textpb
```

Other ways to build:

- **A static Linux executable** that runs on any x86_64 distribution with
  nothing else installed: `scripts/build-static.sh`. It needs the
  `x86_64-unknown-linux-musl` target and a musl C compiler; the script's
  header says how to install them, including on macOS.
- **A container image** with the provided `Dockerfile`:
  `docker build -t ferrix .`

Kernel route installation needs Linux and `CAP_NET_ADMIN`; everywhere else
Ferrix is a BGP speaker only. The [installation
guide](docs/content/docs/getting-started/installation.md) and the
[deployment guide](docs/content/docs/operations/deployment.md) cover
privileges, the systemd unit, and upgrading without withdrawing routes.

## Documentation

The documentation is a website built from [`docs/`](docs/) with
[Zola](https://www.getzola.org): `zola --root docs serve`, then open
<http://127.0.0.1:1111>. The sources are Markdown with Zola front matter,
shortcodes and internal links, so the forge shows them with those parts
unrendered; [`docs/README.md`](docs/README.md) explains what each is. The
pages:

- [Overview](docs/content/docs/getting-started/introduction.md),
  [installation](docs/content/docs/getting-started/installation.md) and
  [quick start](docs/content/docs/getting-started/quick-start.md)
- User guide: [BGP neighbors](docs/content/docs/guides/peers.md),
  [import policy](docs/content/docs/guides/import-policy.md),
  [BGP roles](docs/content/docs/guides/roles.md),
  [RPKI](docs/content/docs/guides/rpki.md),
  [kernel route installation](docs/content/docs/guides/kernel.md),
  [route advertisement](docs/content/docs/guides/passing-routes-on.md),
  [graceful restart](docs/content/docs/guides/graceful-restart.md),
  [configuration examples](docs/content/docs/guides/examples.md)
- [Deployment](docs/content/docs/operations/deployment.md) and
  [monitoring](docs/content/docs/operations/monitoring.md)
- Reference: [configuration](docs/content/docs/reference/configuration.md),
  [command line](docs/content/docs/reference/command-line.md),
  [HTTP API](docs/content/docs/reference/http-api.md),
  [metrics](docs/content/docs/reference/metrics.md),
  [supported standards](docs/content/docs/reference/rfcs.md)
- [Architecture](docs/content/docs/development/architecture.md),
  [testing](docs/content/docs/development/testing.md) and
  [contributing](docs/content/docs/development/contributing.md)

Complete configurations for an edge router, an exchange router and a
transit customer are in [`docs/examples/`](docs/examples/); CI checks that
each of them loads.

## Security

- The status page and HTTP API are not authenticated and show the whole
  configuration and routing table. Bind `http_endpoint` to a loopback
  address, or put it behind a proxy that authenticates.
- Ferrix does not implement TCP-MD5 or TCP-AO. Filter TCP port 179 in the
  host firewall so that only configured neighbors can connect.
- Everything read from the network, the RPKI cache, and the kernel is
  parsed without panicking; each parser has property tests and a fuzz
  target. `unsafe` code is forbidden throughout.

If you find a vulnerability, please contact the maintainer directly rather
than opening a public issue.

## Layout

| Crate                      | What is in it                                                              |
| -------------------------- | -------------------------------------------------------------------------- |
| `crates/primitives`        | Prefixes, address families, parsing helpers                                |
| `crates/packet`            | The wire format: messages, attributes, capabilities                        |
| `crates/rib`               | The routing table, best route selection, the journal of changes            |
| `crates/rpki`              | The RTR client; origin validation and ASPA path verification               |
| `crates/fib`               | The best routes in the Linux kernel, over netlink                          |
| `crates/server`            | Sessions, the state machine, policy, configuration                         |
| `crates/web`               | The status page, HTTP API and metrics                                      |
| `crates/integration-tests` | A test server and test peers, and the tests that run the daemon end to end |
| `crates/bench`             | Benchmarks at the scale of the Internet routing table                      |
| `bin/bgp`                  | The daemon                                                                 |

## Development

CI runs these on every push, and fails on any warning:

```bash
cargo fmt --all -- --check
cargo clippy --locked --workspace --all-targets -- -D warnings
cargo test --locked --workspace
RUSTDOCFLAGS="-D warnings" cargo doc --locked --workspace --no-deps --document-private-items
zola --root docs build
```

It also runs the tests that need a real Linux kernel
(`scripts/kernel-tests.sh`) and a lab that peers the daemon with FRR, BIRD
and Routinator (`scripts/interop/lab.sh`); `scripts/linux-vm.sh` runs
either from macOS in a Lima VM.

`cargo test` includes property tests: generated messages must survive being
written and read back, and no input, however damaged, may make a parser
panic. They take about a second; for a longer hunt:

```bash
PROPTEST_CASES=1000000 cargo test --release -p bgp-packet --test properties
```

Coverage-guided fuzz targets for the same parsers are in `fuzz/`; see
[`fuzz/README.md`](fuzz/README.md). CI runs each of them for a minute.

### Development with AI agents

Much of Ferrix is written with an AI coding agent (Claude Code) working
alongside the maintainer, who directs the work, reviews every change, and
runs the result on real routers. Nothing is merged on the agent's say-so:
every change passes the checks above, the kernel tests and the
interoperability lab, and the changes that matter are tried on the network
first. Commits made with an agent carry a `Co-Authored-By` trailer that
says so. If you contribute, you are welcome to work the same way, or not;
what is reviewed is the change, not how it was produced.

## License

Apache License 2.0; see [`LICENSE`](LICENSE).